Treasury Secretary Steven Mnuchin has resumed discussions with his Chinese counterpart, Vice Premier Liu He, about a deal that would ease trade tension, ahead of a meeting of the leaders of China and the U.S. set for the end of the month.

The two spoke by telephone on Friday, said people briefed on the conversation, as the U.S. demands that China put forward a concrete offer before negotiations on a trade deal can take place. Chinese officials are resisting and say they want to talk first before making a formal proposal. They...